Evaluate immunoprophylactic & chemotherapeutic materials by developing experimental infectious challenge systems for Mycoplasma pneumoniae. Perform systematic evaluation of effect of method of administering vaccines on quantity & duration of humoral & secretory antibodies produced. Develop capability & assess the importance of cellular immune mechanisms in individuals vaccinated & infected with viral & mycoplasmal agents. Evaluate efficacy of topical administration of poly I: poly C against induced rhinovirus & influenza virus infections in man. Study biology of human infection with equine & in human strains of influenza virus. Evaluate live and inactivated vaccines for reactogenicity and immunogenicity in man. Evaluate chemoprophylactic and chemotherapeutic agents that appear useful for human respiratory virus infection.